Radio receiver utilizing a single analog to digital converter

ABSTRACT

A radio receiver includes a low noise amplifier, intermediate frequency mixing stage, complex bandpass filter, a single analog to digital converter, a 1 st  digital mixing module, and a 2 nd  digital mixing module. The low noise amplifier is operably coupled to amplify a modulated radio frequency (RF) signal to produce an amplified modulated RF signal. The intermediate frequency mixing stage is operably coupled to mix the amplified modulated RF signal with a local oscillation to produce a modulated IF signal. The complex bandpass filter filters an I and Q component of the modulated IF signal to produce a filtered IF signal. The single analog to digital converter is operably coupled to convert the filtered IF signal into a digital IF signal. The 1 st  and  2   nd  mixing modules each receive the digital IF signal and mix the digital IF signal with an in-phase and quadrature digital local oscillation to produce a 1 st  baseband signal component and a 2 nd  baseband signal component.

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to communication systems and moreparticularly to radio receivers used within such communication systems.

BACKGROUND OF THE INVENTION

Communication systems are known to support wireless and wire linedcommunications between wireless and/or wire lined communication devices.Such communication systems range from national and/or internationalcellular telephone systems to the Internet to point-to-point in-homewireless networks. Each type of communication system is constructed, andhence operates, in accordance with one or more communication standards.For instance, wireless communication systems may operate in accordancewith one or more standards including, but not limited to, IEEE 802.11,Bluetooth, advanced mobile phone services (AMPS), digital AMPS, globalsystem for mobile communications (GSM), code division multiple access(CDMA), local multi-point distribution systems (LMDS),multi-channel-multi-point distribution systems (MMDS), and/or variationsthereof.

Depending on the type of wireless communication system, a wirelesscommunication device, such as a cellular telephone, two-way radio,personal digital assistant (PDA), personal computer (PC), laptopcomputer, home entertainment equipment, et cetera communicates directlyor indirectly with other wireless communication devices. For directcommunications (also known as point-to-point communications), theparticipating wireless communication devices tune their receivers andtransmitters to the same channel or channels (e.g., one of the pluralityof radio frequency (RF) carriers of the wireless communication system)and communicate over that channel. For indirect wireless communications,each wireless communication device communicates directly with anassociated base station (e.g., for cellular services) and/or anassociated access point (e.g., for an in-home or in-building wirelessnetwork) via an assigned channel. To complete a communication connectionbetween the wireless communication devices, the associated base stationsand/or associated access points communicate with each other directly,via a system controller, via the public switch telephone network, viathe internet, and/or via some other wide area network.

For each wireless communication device to participate in wirelesscommunications, it includes a built-in radio transceiver (i.e., receiverand transmitter) or is coupled to an associated radio transceiver (e.g.,a station for in-home and/or in-building wireless communicationnetworks, RF modem, etc.). As is known, the transmitter converts datainto RF signals by modulating the data in accordance with the particularwireless communication standard to an RF carrier directly or in one ormore intermediate frequency stages to produce the RF signals.

As is also known, the receiver receives RF signals, removes the RFcarrier frequency from the RF signals via one or more intermediatefrequency (IF) stages to produce analog baseband signals, converts theanalog low IF signals into digital low IF signals, and demodulates thedigital baseband signals in accordance with a particular wirelesscommunication standard to recapture the transmitted data. The analog lowIF signals include an in-phase (I) component and a quadrature (Q)component. As such, the receiver includes two analog to digital convertsto convert the analog I and Q signals into digital I and Q signals.

The demands for enhanced performance smaller sizes, lower powerconsumption, and reduced costs of wireless communication devices areincreasing. As such, stringent performance and size criteria are placedon the components comprising the wireless communication device. Forexample, the performance requirements for the analog to digital convertsto convert the analog I and Q signal components into digital signals arequite stringent requiring a complex circuit implementation. Such acomplex circuit implementation requires a relatively large silicon area(i.e., integrated circuit real estate) and consumes a relativelysignificant amount of power.

Therefore, a need exists for reducing size and power consumption of theanalog to digital conversion process in radio receivers.

SUMMARY OF THE INVENTION

The radio receiver including a single analog to digital converter asdisclosed herein substantially meets these needs and others. Such aradio receiver includes a low noise amplifier, intermediate frequencymixing stage, complex bandpass filter, a single analog to digitalconverter, a 1^(st) digital mixing module, and a 2^(nd) digital mixingmodule. The low noise amplifier is operably coupled to amplify amodulated radio frequency (RF) signal to produce an amplified modulatedRF signal. The modulated RF signal may be modulated in accordance withany one of a plurality of wireless communication standards including,but not limited to, Bluetooth, 802.11a, 802.11b, et cetera.

The intermediate frequency mixing stage is operably coupled to mix theamplified modulated RF signal with a local oscillation to produce amodulated IF signal. The local oscillation is selected to be of afrequency such that the difference between the frequency of the RFsignal and the frequency of the local oscillation produces theintermediate frequency.

The complex bandpass filter filters an I and Q component of themodulated IF signal to produce a filtered IF signal. The complexbandpass filter filters the I and Q components in such a way to producea single filtered IF signal, which contains the I and Q information.

A single analog to digital converter is operably coupled to convert thefiltered IF signal into a digital IF signal. The 1^(st) and 2^(nd)mixing modules each receive the digital IF signal and mix the digital IFsignal with an in-phase and quadrature digital local oscillation toproduce a 1^(st) baseband signal component and a 2^(nd) baseband signalcomponent. For example, the 1^(st) baseband signal component may be anin-phase baseband digital signal and the 2^(nd) baseband signalcomponent may be a quadrature baseband signal.

In an alternative embodiment, an apparatus for digital intermediatefrequency to baseband conversion of a single digital IF signal includesprocessing that enables the apparatus to receive a single digital IFsignal that corresponds to a modulated radio frequency signal. Theprocessing further enables the apparatus to mix the single digital IFsignal with a 1^(st) digital local oscillation to produce a 1^(st)digitally mixed signal. The processing further allows the apparatus tomix the single digital IF signal with a 2^(nd) digital local oscillationto produce a 2^(nd) digitally mixed signal. The processing furtherallows the apparatus to perform a decimation filter upon the 1^(st) and2^(nd) digitally mixed signals to produce 1^(st) and 2^(nd) basebandsignal components. The 1^(st) and 2^(nd) baseband signal components maybe further processed to recapture transmitted data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic block diagram of a communication systemin accordance with the present invention;

FIG. 2 illustrates a schematic block diagram of a wireless communicationdevice in accordance with the present invention;

FIG. 3 illustrates a schematic block diagram that further illustratesthe receiver section of the wireless communication device of FIG. 2;

FIG. 4 illustrates a schematic block diagram of an analog to digitalconverter in accordance with the present invention;

FIG. 5 illustrates a schematic block diagram of a low pass filter inaccordance with the present invention; and

FIG. 6 illustrates a logic diagram of a method for processingintermediate frequency signals from a single analog to digital converterin accordance with the present invention.

DETAIL DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 illustrates a schematic block diagram of a communication system10 that includes a plurality of base stations and/or access points12-16, a plurality of wireless communication devices 18-32 and a networkhardware component 34. The wireless communication devices 18-32 may belaptop host computers 18 and 26, personal digital assistant hosts 20 and30, personal computer hosts 24 and 32 and/or cellular telephone hosts 22and 28. The details of the wireless communication devices will bedescribed in greater detail with reference to FIG. 2.

The base stations or access points 12 are operably coupled to thenetwork hardware 34 via local area network connections 36, 38 and 40.The network hardware 34, which may be a router, switch, bridge, modem,system controller, et cetera provides a wide area network connection 42for the communication system 10. Each of the base stations or accesspoints 12-16 has an associated antenna or antenna array to communicatewith the wireless communication devices in its area. Typically, thewireless communication devices register with a particular base stationor access point 12-14 to receive services from the communication system10. For direct connections (i.e., point-to-point communications),wireless communication devices communicate directly via an allocatedchannel.

Typically, base stations are used for cellular telephone systems andlike-type systems, while access points are used for in-home orin-building wireless networks. Regardless of the particular type ofcommunication system, each wireless communication device includes abuilt-in radio and/or is coupled to a radio. The radio includes a highlylinear amplifier and/or programmable multi-stage amplifier as disclosedherein to enhance performance, reduce costs, reduce size, and/or enhancebroadband applications.

FIG. 2 illustrates a schematic block diagram of a wireless communicationdevice that includes the host device 18-32 and an associated radio 60.For cellular telephone hosts, the radio 60 is a built-in component. Forpersonal digital assistants hosts, laptop hosts, and/or personalcomputer hosts, the radio 60 may be built-in or an externally coupledcomponent.

As illustrated, the host device 18-32 includes a processing module 50,memory 52, radio interface 54, input interface 58 and output interface56. The processing module 50 and memory 52 execute the correspondinginstructions that are typically done by the host device. For example,for a cellular telephone host device, the processing module 50 performsthe corresponding communication functions in accordance with aparticular cellular telephone standard.

The radio interface 54 allows data to be received from and sent to theradio 60. For data received from the radio 60 (e.g., inbound data), theradio interface 54 provides the data to the processing module 50 forfurther processing and/or routing to the output interface 56. The outputinterface 56 provides connectivity to an output display device such as adisplay, monitor, speakers, et cetera such that the received data may bedisplayed. The radio interface 54 also provides data from the processingmodule 50 to the radio 60. The processing module 50 may receive theoutbound data from an input device such as a keyboard, keypad,microphone, et cetera via the input interface 58 or generate the dataitself. For data received via the input interface 58, the processingmodule 50 may perform a corresponding host function on the data and/orroute it to the radio 60 via the radio interface 54.

Radio 60 includes a host interface 62, digital receiver processingmodule 64, a single analog-to-digital converter 66, a complex bandpassfilter 68, IF mixing stage 70, a receiver filter 71, a low noiseamplifier 72, a transmitter filter 73, local oscillation module 74,memory 75, digital transmitter processing module 76, atransmitter/receiver switch 77, digital-to-analog converter 78,filtering/gain module 80, IF mixing stage 82, power amplifier 84, and anantenna 86. The antenna 86 may be a single antenna that is shared by thetransmit and receive paths as regulated by the Tx/Rx switch 77, or mayinclude separate antennas for the transmit path and receive path. Theantenna implementation will depend on the particular standard to whichthe wireless communication device is compliant.

The digital receiver processing module 64 and the digital transmitterprocessing module 76, in combination with operational instructionsstored in memory 75, execute digital receiver functions and digitaltransmitter functions, respectively. The digital receiver functionsinclude, but are not limited to, digital intermediate frequency tobaseband conversion, demodulation, constellation demapping, decoding,and/or descrambling. The digital transmitter functions include, but arenot limited to, scrambling, encoding, constellation mapping, modulation,and/or digital baseband to IF conversion. The digital receiver andtransmitter processing modules 64 and 76 may be implemented using ashared processing device, individual processing devices, or a pluralityof processing devices. Such a processing device may be a microprocessor,micro-controller, digital signal processor, microcomputer, centralprocessing unit, field programmable gate array, programmable logicdevice, state machine, logic circuitry, analog circuitry, digitalcircuitry, and/or any device that manipulates signals (analog and/ordigital) based on operational instructions. The memory 75 may be asingle memory device or a plurality of memory devices. Such a memorydevice may be a read-only memory, random access memory, volatile memory,non-volatile memory, static memory, dynamic memory, flash memory, and/orany device that stores digital information. Note that when theprocessing module 64 and/or 76 implements one or more of its functionsvia a state machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory storing the corresponding operational instructionsis embedded with the circuitry comprising the state machine, analogcircuitry, digital circuitry, and/or logic circuitry. The memory 75stores, and the processing module 64 and/or 76 executes, operationalinstructions corresponding to at least some of the functions illustratedin FIGS. 3-6.

In operation, the radio 60 receives outbound data 94 from the hostdevice via the host interface 62. The host interface 62 routes theoutbound data 94 to the digital transmitter processing module 76, whichprocesses the outbound data 94 in accordance with a particular wirelesscommunication standard (e.g., IEEE802.11a, IEEE802.11b, Bluetooth, etcetera) to produce digital transmission formatted data 96. The digitaltransmission formatted data 96 will be a digital base-band signal or adigital low IF signal, where the low IF typically will be in thefrequency range of one hundred kilohertz to a few megahertz.

The digital-to-analog converter 78 converts the digital transmissionformatted data 96 from the digital domain to the analog domain. Thefiltering/gain module 80 filters and/or adjusts the gain of the analogsignal prior to providing it to the IF mixing stage 82. The IF mixingstage 82 directly converts the analog baseband or low IF signal into anRF signal based on a transmitter local oscillation 83 provided by localoscillation module 74. The power amplifier 84 amplifies the RF signal toproduce outbound RF signal 98, which is filtered by the Tx filter 73.The antenna 86 transmits the outbound RF signal 98 to a targeted devicesuch as a base station, an access point and/or another wirelesscommunication device.

The radio 60 also receives an inbound RF signal 85 via the antenna 86,which was transmitted by a base station, an access point, or anotherwireless communication device. The antenna 86 provides the inbound RFsignal 85 to the Rx filter 71 via the Tx/Rx switch 77, where the Rxfilter 71 bandpass filters the inbound RF signal 85. The Rx filter 71provides the filtered RF signal to low noise amplifier 72, whichamplifies the signal 88 to produce an amplified inbound RF signal. Thelow noise amplifier 72 provide the amplified inbound RF signal to the IFmixing module 70, which directly converts the amplified inbound RFsignal into an inbound low IF signal based on a receiver localoscillation 81 provided by local oscillation module 74. The downconversion module 70 provides the inbound low IF signal to the complexbandpass filter 68. The complex bandpass filter 68 may be of the typedisclosed in copending patent application entitled “Adaptive RadioTransceiver with Filtering” having a serial number of Ser. No.09/692,420 and a filing date of Oct.19, 2000. In general, the complexbandpass filter 68 filters analog I and Q components to produce a singlecomplex analog signal (e.g., a filtered IF signal 88) that retains theinformation of the I and Q components.

The single analog-to-digital converter 66 converts the filtered inboundlow IF signal from the analog domain to the digital domain to producedigital reception formatted data 90. The digital receiver processingmodule 64 decodes, descrambles, demaps, and/or demodulates the digitalreception formatted data 90 to recapture inbound data 92 in accordancewith the particular wireless communication standard being implemented byradio 60. The host interface 62 provides the recaptured inbound data 92to the host device 18-32 via the radio interface 54.

FIG. 3 illustrates a schematic block diagram of a portion of the radioreceiver of the wireless communication device of FIG. 2. The portionillustrated includes the complex bandpass filter 68, the single analogto digital converter 66, the digital receiver processing module 64 andmemory 75. The complex bandpass filter 68, which may be a polyphasefilter that filters an I component and a Q component of the modulated IFsignal to produce a single filtered IF signal may be described inco-pending patent application entitled ADAPTIVE RADIO TRANSCEIVER WITHFILTERING, having a serial number of Ser. No. 09/692,420 and a filingdate of Oct. 19, 2000. The complex bandpass filter 68 provides thefiltered IF signal 88 to the analog to digital converter 66. Note thatthe filtered IF signal 88 is a single signal that contains I and Qinformation of the modulated IF signal 87.

The analog to digital converter 66 converts the filtered IF signal 88into a digital IF signal. The analog to digital converter 66, may beconstructed in accordance with any type of analog to digital convertertopology including continuous time Delta Sigma analog to digitalconverters, flash analog to digital converters. For instance, asillustrated in FIG. 4 and will be described below, the analog to digitalconverter 66 may be a continuous time Delta Sigma analog to digitalconverter.

The digital receiver processing module 64 is configured and/orconstructed to include a 1^(st) digital mixing module 100, a 2^(nd)digital mixing module 102, a direct digital frequency synthesizer (DDFS)104, and a digital data recovery module 106. The 1^(st) digital mixingmodule 100 includes a digital mixer 112, a low pass decimation filter108 and a digital gain control module 110. The low pass decimationfilter 108 includes a low pass filter 114, which may be implemented asillustrated in FIG. 5, and a down sampling module 116. The 2^(nd)digital mixing module 102 includes a digital mixer 122, a low passdecimation filter 118, and a digital gain control module 120. The lowpass decimation filter 118 includes a low pass filter 124, which may beimplemented as illustrated in FIG. 5, and a down sampling module 126.

In operation, the analog to digital converter 66 provides the digital IFsignal to the 1^(st) digital mixing module and to the 2^(nd) digitalmixing module. Within the 1^(st) digital mixing module 100, digitalmixer 112 mixes the digital IF signal with an in-phase digital localoscillation, which is produced by the direct digital frequencysynthesizer 104, to produce a 1^(st) mixed signal at baseband. Note thatutilizing a lookup table may perform the multiplication performed by thedigital mixer via the direct digital frequency synthesizer. The low passdecimation filter 108 processes the 1^(st) mixed signal via the low passfilter 114 and the down sampling module 116 to produce a decimated mixedsignal. The down sampling module 116 may be a down convert by 4 modulesuch that the resulting rate of the decimated mixed signal is ¼^(th) ofthe rate of the 1^(st) mixed signal.

The digital gain control module 110 adjusts the magnitude of thedecimated mixed signal to produce the 1 ^(st) baseband signal component128. The gain control module 110 amplifies the baseband signal, i.e.,the output of the low pass decimation filter 108, to a level appropriatefor baseband processing by the digital data recovery module 106. Theappropriate level is at least partially dependent on the particularmodulation scheme prescribed by the corresponding wireless communicationstandard, the supply voltages of the radio frequency integrated circuitembodying the radio receiver of FIG. 3, and/or sensitivity of thecircuitry within the digital data recovery module 106.

Within the 2^(nd) digital mixing module 102, digital mixer 122 mixes thedigital IF signal with a quadrature digital local oscillation, which isproduced by the direct digital frequency synthesizer 104, to produce a2^(nd) mixed signal at baseband. Note that utilizing a lookup table mayperform the multiplication performed by the digital mixer via the directdigital frequency synthesizer. The low pass decimation filter 118processes the 2^(nd) mixed signal via the low pass filter 124 and thedown sampling module 126 to produce a decimated mixed signal. The downsampling module 126 may be a down convert by 4 module such that theresulting rate of the decimated mixed signal is ¼^(th) of the rate ofthe 2^(nd) mixed signal.

The digital gain control module 120 adjusts the magnitude of thedecimated mixed signal to produce the 2^(nd) baseband signal component130. The gain control module 120 amplifies the baseband signal, i.e.,the output of the low pass decimation filter 118, to a level appropriatefor baseband processing by the digital data recovery module 106. Theappropriate level is at least partially dependent on the particularmodulation scheme prescribed by the corresponding wireless communicationstandard, the supply voltages of the radio frequency integrated circuitembodying the radio receiver of FIG. 3, and/or sensitivity of thecircuitry within the digital data recovery module 106.

The digital data recovery module 106 receives the 1^(st) baseband signalcomponent 128 and the 2^(nd) baseband signal component 130 and producestherefrom inbound data 92. The digital data recovery module 106 decodesthe 1^(st) and 2^(nd) baseband signal components in accordance with theparticular wireless communication standard being implemented by thewireless communication device of FIG. 2.

FIG. 4 illustrates a schematic block diagram of one embodiment of theanalog to digital converter 66. In this embodiment, the analog todigital converter is a 2^(nd) order continuous time Delta Sigmamodulator. As shown, the analog to digital converter 66 includes 1^(st)and 2^(nd) gain stages 140 and 144, 1^(st) and 2^(nd) integrators 142and 146, a quantizer 148 and 1^(st) and 2^(nd) digital to analogconverters 150 and 152. As configured, the analog to digital converter66 receives the filtered IF signal 88 and produces a 2-bit digital IFsignal 90. The quantization may be performed at 13 MHz. As one ofaverage skill in the art will appreciate, the quantization rate may varyfrom the 13 MHz as well as the order of the continuous time Delta Sigmamodulator.

FIG. 5 illustrates an embodiment of the low pass filters 114 and 124 andincludes a differentiation module and a plurality of cascaded combfilters to provide the low pass filtering. As one of average skill inthe art will appreciate, the number of cascaded comb filters may varyfrom those shown as well as the order of the low pass filter.

FIG. 6 illustrates a logic diagram of a method for intermediatefrequency to baseband conversion from a single digital IF signal. Theprocess begins at Step 160 where a single digital IF signal thatcorresponds to a modulated RF signal is received. For instance, thesingle digital IF signal may be received from a single analog to digitalconverter that has converted a filtered IF signal into the singledigital IF signal. The filtered IF signal may be produced by a complexbandpass filter that filtered an I and Q component of the modulated IFsignal, which is representative of the modulated RF signal.

The process then proceeds to Steps 162 and 164. At Step 162, the singledigital IF signal is mixed with a 1^(st) digital local oscillation toproduce a 1^(st) digitally mixed signal. At Step 164, the single digitalIF signal is mixed with a 2^(nd) digital local oscillation to produce a2^(nd) digitally mixed signal.

The process proceeds from Step 162 to Step 166 where the 1^(st)digitally mixed signal is decimation filtered to produce a ₁St basebandcomponent signal. The decimation filtering may be done by low passfiltering the digitally mixed signal to produce a low pass filteredsignal. The low pass filter signal may then be down sampled to producethe 1^(st) baseband signal component.

From Step 164, the process proceeds to Step 168 where the 2^(nd)digitally mixed signal is decimation filtered to produce a 2^(nd)baseband signal component. The decimation filtering may be done by lowpass filtering the 2^(nd) digitally mixed signal to produce a filteredsignal. The filtered signal is then down sampled to produce the 2^(nd)baseband signal component.

The preceding discussion has presented a radio receiver that utilizes asingle analog to digital converter, which reduces power consumption,reduces integrated circuit size, and provides other benefits. As one ofaverage skill in the art will appreciate, other embodiments may bederived from the teaching of the present invention, without deviatingfrom the scope of the claims.

1. A radio receiver comprises: low noise amplifier operably coupled toamplify a modulated radio frequency (RF) signal to produce an amplifiedmodulated RF signal; intermediate frequency (IF) mixing stage operablycoupled to mix the amplified modulated RF signal with a localoscillation to produce a modulated IF signal; complex bandpass filteroperably coupled to filter the modulated IF signal to produce a filteredIF signal, wherein the filtered IF signal includes information regardingan in-phase component and a quadrature component of the amplifiedmodulated RF signal; an analog to digital converter operably coupled toconvert the filtered IF signal into a digital IF signal; first digitalmixing module operably coupled to process the digital IF signal with anin-phase digital local oscillation to produce a first baseband signalcomponent; and second digital mixing module operably coupled to processthe digital IF signal with a quadrature digital local oscillation toproduce a second baseband signal component.
 2. The radio receiver ofclaim 1, wherein the complex bandpass filter further comprises: a polyphase filter operably coupled to filter an I component and a Q componentof the modulated IF signal.
 3. The radio receiver of claim 1, whereinthe analog to digital converter further comprises one of: continuoustime delta sigma analog to digital converter; or flash analog to digitalconverter.
 4. The radio receiver of claim 1, wherein the first digitalmixing module further comprises: digital mixer operably coupled to mixthe digital IF signal with the in-phase digital local oscillation toproduce a first mixed signal; low pass decimation filter operablycoupled to process the first mixed signal to produce a decimated mixedsignal; and digital gain control module operably coupled to adjustmagnitude of the decimated mixed signal to produce the first basebandsignal component.
 5. The radio receiver of claim 4, wherein the low passdecimation filter further comprises: low pass filter operably coupled tolow pass filter the first mixed signal to produce a filtered mixedsignal; and down sampling module operably coupled to down sample thefiltered mixed signal to produce the decimated mixed signal.
 6. Theradio receiver of claim 1, wherein the second digital mixing modulefurther comprises: digital mixer operably coupled to mix the digital IFsignal with the quadrature digital local oscillation to produce a secondmixed signal; low pass decimation filter operably coupled to process thesecond mixed signal to produce a decimated mixed signal; and digitalgain control module operably coupled to adjust magnitude of thedecimated mixed signal to produce the second baseband signal component.7. The radio receiver of claim 6, wherein the low pass decimation filterfurther comprises: low pass filter operably coupled to low pass filterthe second mixed signal to produce a filtered mixed signal; and downsampling module operably coupled to down sample the filtered mixedsignal to produce the decimated mixed signal.
 8. The radio receiver ofclaim 1, wherein the IF mixing stage further comprises: quadrature mixeroperably coupled to produce the modulated IF signal, wherein the complexbandpass filter is centered at the intermediate frequency that is atleast half of bandwidth of the modulated RF signal, and wherein thequadrature mixer in combination with the complex bandpass filter rejectinterference signals at image frequencies.
 9. A method for digitalintermediate frequency (IF) to baseband conversion from a single digitalIF signal, the method comprises: receiving the single digital IF signalthat corresponds to a modulated radio frequency (RF) signal, wherein thesingle digital IF signal includes information of an in-phase componentand a quadrature component of the RF signal, wherein receiving thesingle digital IF signal includes: band pass filtering a modulated IFsignal to produce a filtered IF signal; and analog to digitallyconvening the filtered IF signal into the single digital IF signal;mixing the single digital IF signal with a first digital localoscillation to produce a first digitally mixed signal; mixing the singledigital IF signal with a second digital local oscillation to produce asecond digitally mixed signal; decimation filtering the first digitallymixed signal to produce a first baseband signal component; anddecimation filtering the second digitally mixed signal to produce asecond baseband signal component.
 10. The method of claim 9 furthercomprises: adjusting gain of the first baseband signal component inaccordance with baseband processing; and adjusting gain of the secondbaseband signal component in accordance with the baseband processing.11. The method of claim 9, wherein the decimation filtering of the firstdigitally mixed signal further comprises: low pass filtering the firstdigitally mixed signal to produce a filtered signal; and down samplingthe filtered signal to produce the first baseband signal component. 12.The method of claim 9, wherein the decimation filtering of the seconddigitally mixed signal further comprises: low pass filtering the seconddigitally mixed signal to produce a filtered signal; and down samplingthe filtered signal to produce the second baseband signal component. 13.An apparatus for digital intermediate frequency (IF) to basebandconversion from a single digital IF signal, the apparatus comprises:processing module; and memory operably coupled to the processing module,wherein the memory includes operational instructions that cause theprocessing module to: receive the single digital IF signal thatcorresponds to a modulated radio frequency (1(F) signal by band-passfiltering a modulated IF signal to produce a filtered IF signal, andanalog to digitally convening the filtered IF signal into the singledigital IF signal, wherein the single digital IF signal includesinformation of an in-phase component and a quadrature component of theRF signal; mix the single digital IF signal with a first digital localoscillation to produce a first digitally mixed signal; mix the singledigital IF signal with a second digital local oscillation to produce asecond digitally mixed signal; decimation filter the first digitallymixed signal to produce a first baseband signal component; anddecimation filter the second digitally mixed signal to produce a secondbaseband signal component.
 14. The apparatus of claim 13, wherein thememory further comprises operational instructions that cause theprocessing module to: adjust gain of the first baseband signal componentin accordance with baseband processing; and adjust gain of the secondbaseband signal component in accordance with the baseband processing.15. The apparatus of claim 13, wherein the memory further comprisesoperational instructions that cause the processing module to decimationfilter the first digitally mixed signal by: low pass filtering the firstdigitally mixed signal to produce a filtered signal; and down samplingthe filtered signal to produce the first baseband signal component. 16.The apparatus of claim 13, wherein the memory further comprisesoperational instructions that cause the processing module to decimationfilter the second digitally mixed signal by: low pass filtering thesecond digitally mixed signal to produce a filtered signal; and downsampling the filtered signal to produce the second baseband signalcomponent.
 17. A radio receiver comprises: low noise amplifier operablycoupled to amplify a modulated radio frequency (RF) signal to produce anamplified modulated RF signal; intermediate frequency (IF) mixing stageoperably coupled to mix the amplified modulated RF signal with a localoscillation to produce a modulated IF signal; complex bandpass filteroperably coupled to filter the modulated IF signal to produce a filteredIF signal, wherein the filtered IF signal includes information regardingan in-phase component and a quadrature component of the amplifiedmodulated RF signal; an analog to digital converter operably coupled toconvert the filtered IF signal into a digital IF signal; and digitalprocessing module operably coupled to produce a first baseband componentand a second baseband component from the digital IF signal.
 18. Theradio receiver of claim 17, wherein the complex bandpass filter furthercomprises: a poly phase filter operably coupled to filter an I componentand a Q component of the modulated IF signal.
 19. The radio receiver ofclaim 17, wherein the analog to digital converter further comprises oneof: continuous time delta sigma analog to digital converter; or flashanalog to digital converter.
 20. The radio receiver of claim 17, whereinthe digital processing module further comprises: memory operably coupledto the digital processing module, wherein the memory includesoperational instructions that cause the digital processing module to:mix the digital IF signal with a first digital local oscillation toproduce a first digitally mixed signal; mix the digital IF signal with asecond digital local oscillation to produce a second digitally mixedsignal; decimation filter the first digitally mixed signal to producethe first baseband signal component; and decimation filter the seconddigitally mixed signal to produce the second baseband signal component.21. The radio receiver of claim 20, wherein the memory further comprisesoperational instructions that cause the digital processing module to:adjust gain of the first baseband signal component in accordance withbaseband processing; and adjust gain of the second baseband signalcomponent in accordance with the baseband processing.
 22. The radioreceiver of claim 20, wherein the memory further comprises operationalinstructions that cause the digital processing module to decimationfilter the first digitally mixed signal by: low pass filtering the firstdigitally mixed signal to produce a filtered signal; and down samplingthe filtered signal to produce the first baseband signal component. 23.The radio receiver of claim 20, wherein the memory further comprisesoperational instructions that cause the digital processing module todecimation filter the second digitally mixed signal by: low passfiltering the second digitally mixed signal to produce a filteredsignal; and down sampling the filtered signal to produce the secondbaseband signal component.